I know you didn't want advice on fish habits or whatever, but I have no idea what you may or may not know about the BGK and I am concerned over the health of any fish in an aquarium, so I hope you'll permit me some comments.

At close to 20 inches mature size--assuming it is healthy and develops properly--it will need a tank that is at minimum 6 feet long and 2 feet wide; being inflexible, it cannot turn around in anything less. As for the driftwood, this fish is nocturnal and will try to remain hidden in bright light--or will if it is healthy; a fish that swims around the tank in light is not healthy but stressed. And naturally living among sunken branches and roots, this is natural. Dim light, helped with a good cover of floating plants, is essential for this fish to be stress-free (which equals healthy). You can read more in our profile, click the shaded name Black Ghost Knifefish.

The aquarist is one who must learn the ways of the biologist, the chemist, and the veterinarian.[unknown source]

Something we all need to remember: The fish you've acquired was quite happy not being owned by you, minding its own business. If you’re going to take it under your wing then you’re responsible for it. Every aspect of its life is under your control, from water quality and temperature to swimming space. [Nathan Hill in PFK]